On-vehicle image pick-up apparatus and method of setting image pick-up direction

ABSTRACT

A prism for reflecting rays of light  17 L and  17 R incident from left and right image pick-up directions on the rear side of the direction of travel A is disposed in parallel to the vertical direction of a vehicle. The image pick-up optical axis of an image pick-up unit  15  is set to tilt vertically and obliquely with respect to a horizontal plane C, whereby the images in the respective image pick-up directions which are obliquely above or below the horizontal plane are picked up by the image pick-up unit  15.

This is a Division of Application No. 09/827,941 filed Apr. 9, 2001 nowU.S. Pat. 6,657,176. The entire disclosure of the prior application ishereby incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an on-vehicle image pick-up apparatusfor picking up a dead angle area on left and right sides on the forwardor backward side of a vehicle and a method of setting an image pick-updirection.

2. Description of the Related Art

When an automobile approaches an intersection, normally it will benecessary for a driver to ensure safety on left and right sides. At anyintersection offering poor lateral visibility, however, the driver hashad to cause the vehicle to enter the intersection zone a little bit soas to make sure of safety on left and right sides. Consequently, thedriver needs paying careful attention to moving the vehicle into theintersection zone and also making sure of safety by directly watchingscenes on both the left and right sides after entering the intersectionzone, which has mentally given the driver a burden.

In order to reduce the aforementioned burden, there have recently beenproposed a system of displaying images on the left and right sides of avehicle, which images are picked up by image pick-up sensors such asCCDs fitted in the holes bored in the respective sides of an automotivebumper and displayed on a display unit such as a two-plane televisioninstalled in the vehicle; and a system of simultaneously displayingimages on the left and right sides of a vehicle on a display unitprovided in the vehicle by attaching a single image pick-up sensor ontothe periphery of an automotive bumper or front glass and simultaneouslytaking in scenes on the left and right sides of the vehicle by means ofthe image pick-up sensor.

For example, JP-A-10-81173 discloses the former system, whereasJP-A-6-344827 discloses the latter system.

As shown in FIGS. 13 and 14, there has been proposed an apparatus forwatching around a vehicle wherein images in the image pick-up directions3L and 3R corresponding dead angles respectively on both left and rightsides in the direction of travel A of a vehicle are picked up by animage pick-up apparatus 1 installed in the front end portion (frontgrille in this case) of the vehicle and utilized for driving. Such animage pick-up apparatus 1 may otherwise be installed in the rear endportion of a vehicle in order to pick up images in image pick-updirections corresponding dead angles in the direction of moving back avehicle.

FIG. 15 is a block diagram showing the structure of a conventionalapparatus for watching around a vehicle; and FIG. 16, a side view of theprincipal part of what is shown in FIG. 15. The apparatus for watchingaround a vehicle comprises a image pick-up apparatus 1, a processingportion 5, and a display unit 7 installed within a vehicle.

The image pick-up apparatus 1 has a light shielding case 11 providedwith a pair of transmission windows 11L and 11R on both the respectivesides thereof. In this case 11 exists an isosceles triangular prism (areflective unit) 13 in cross section which is housed and placed in sucha posture that its vertical angle side faces the front part of the case11 (upper portion of the case 11 in FIG. 15) and that the lateral sides(first reflective surfaces) 13L and 13R of the prism corresponding tothe isosceles of the isosceles triangle faces the respectivetransmission windows 11L and 11R. An image pick-up unit (an imagepick-up unit) 15 is also housed so that it is positioned on the backside of the prism 13. The image pick-up unit 15 is equipped with animage pick-up element 15 a and an image forming lens 15 b disposed inthe optical paths of rays of light 17L and 17R between the image pick-upelement 15 a and the prism 13.

Rays of light 17L and 17R incident from the image pick-up directions 3Land 3R on the lateral sides of the vehicle are incident onto the prism13 via the both sides 13L and 13R of the prism, respectively. Then therays of light 17L and 17R are wholly reflected from the respective sides13L and 13R of the prism, and the optical paths are changed todirections substantially opposite to the direction of travel of thevehicle before being emitted from the prism 13 and incident on the imagepick-up element 5 a. Thus, images in the respective image pick-updirections 3L and 3R on both left and right sides are picked up by thesingle image pick-up element 15 a.

An image signal that is output from the image pick-up element 15 a isinput to the predetermined processing portion 5 and subjected to apredetermined process such as an inversion process. The processed imagesignal is supplied to the display unit 7, whereby the images in theimage pick-up directions 3L and 3R are displayed by the image pick-upelement 15 a on the respective display areas 7L and 7R of the displayunit 7.

The prism 13 in the conventional apparatus for watching around a vehicleis disposed in the case 11 so that both sides 13L and 13R of the prismmay be laterally symmetrical with respect to the direction of travel Aand in parallel to the vertical direction of the vehicle. Moreover, theimage pick-up optical axis B of the image pick-up unit 15 is setparallel to the direction of travel A so that it may not lean to ahorizontal plane C (see FIG. 17).

Accordingly, rays of light 17L′ and 17R′ on the incident optical axesout of the rays of light 17L and 17R that are reflected from therespective sides 13L and 13R of the prism 13 and incident from the imagepick-up directions 3L and 3R are reflected at the reflective position Pof the sides 13L and 13R of the prism and incident on the image pick-upunit 15 while the rays of light 17L′ and 17R′ are kept parallel to thehorizontal plane C.

In the conventional apparatus for watching around a vehicle, images inthe lateral image pick-up directions 3L and 3R are consequently pickedup in such a state that the image pick-up optical axes defining theimage pick-up directions 3L and 3R have been set parallel to thehorizontal plane C.

FIG. 18 illustrates the state in which the picked up images are beingdisplayed on the display unit 7 in the conventional apparatus forwatching around a vehicle. In FIG. 18, reference numerals 21 and 23refer to the bumper 9 of the vehicle; and 25 and 27 refer to images ofthe obstacles positioned on both left and right sides of the vehicle.

In the apparatus for watching around a vehicle like this, there is acase where the adjustment of the image pick-up directions 3L and 3R maybe necessary by tilting them vertically with respect to the horizontalplane so as to obtain more useful peripheral images depending on thecondition of installation of the image pick-up apparatus 1 including theposition of installation of the image pick-up apparatus 1 on thevehicle, the configuration of the vehicle (configuration of the grilleor the bumper 9 in particular) around the position of installation ofthe image pick-up apparatus and its periphery and so forth.

In the conventional apparatus for watching around a vehicle, however,the images 21 and 23 of the bumper 9 on the picked up image plane aretoo large in percentage and wasteful as shown in FIG. 18 under theinfluence of the conditions of installation of the image pick-upapparatus 1. Therefore, it is necessary to restrain the bumper 9 frombeing taken too much by correcting the image pick-up directions 3L and3R upward.

As a method of changing the image pick-up directions 3L and 3R upward ordownward in the conventional apparatus for watching around a vehicle,what is considered effective is to install the whole image pick-upapparatus 1 tilting in the vertical direction of the vehicle and tochange the image pick-up directions 3L and 3R upward or downward byadjusting the angle of inclination.

However, there arises an inconvenience under the method stated above inthat under an image of any pick-up object (e.g., building or telegraphpole) that actually uprightly exists is picked up and displayed as it istilting with respect to the vertical direction.

This is due to the fact that when the image pick-up apparatus 1 isinstalled in the tilted condition, the sides 13L and 13R of the prism asthe reflective surfaces of the prism 13 are also tilted with respect tothe vertical direction, whereby the tilted image of the pick-up objectis taken on the sides 13L and 13R of the prism when it is reflected fromthe sides 13L and 13R of the prism.

Although there is another method of changing the image pick-updirections 3L and 3R upward or downward with respect to the horizontalplane C by tiltably disposing the prism 13 in the vertical directionwhile the image pick-up optical axis B of the image pick-up unit 15 isheld in parallel to the direction of travel A, the upright image iscaused to tilt by the tilting of the sides 13L and 13R of the prism.

In addition, the following problems might occur in the conventionalimage pick-up apparatus.

1) Such an image pick-up sensor has been embedded in the bumper orfitted to the periphery of the front glass inside the vehicle, the heatradiation efficiency of the image pick-up sensor is poor and this hascaused the performance of the image pick-up sensor to be lowered inhigh-temperature environment in summer. Consequently, it has been neededto improve the heat resistance of the image pick-up sensor, and a heatsink and the like used to cope with this situation have resulted inincreasing the number of parts.

2) In case where rain drops, washing water drops and like stick to theouter surface of such a transmission window because of the rain falling,vehicle body washing and like, it is feared that the pick-up image maybe disturbed by the refraction and scattering of rays of light causedthereby.

SUMMARY OF THE INVENTION

In view of the foregoing problems, an object of the present invention isto provide an on-vehicle image pick-up apparatus capable of settingimage pick-up directions obliquely upward or downward with respect to ahorizontal plane without causing an image of an upright pick-up objectto be tilted and a method of setting image pick-up directions.

Another object of the present invention is to provide an on-vehicleapparatus for watching around a vehicle which keeps vehicle designunaffected while securing a sufficient visual field around a vehicle andis also adapted to improve heat radiation efficiency.

Still another object of the present invention is to provide a vehicularimage pick-up apparatus for allowing less-disturbed images around avehicle to be obtained.

According to the invention, there is provided an on-vehicle imagepick-up apparatus comprising a reflective unit which is provided in thefront or rear end portion of a vehicle and has two first reflectivesurfaces for reflecting rays of light incident from image pick-updirections on both left and right sides of the vehicle respectively in adirection substantially parallel to the longitudinal direction of thevehicle, and an image pick-up unit for picking up images in therespective image pick-up directions by taking in the rays of lightreflected in the reflective unit and is characterized in that the firstreflective surfaces of the reflective unit are disposed in parallel tothe vertical direction of the vehicle; the image pick-up optical axis ofthe image pick-up unit is set so that the incident optical axes of therays of light may tilt vertically and obliquely with respect to ahorizontal plane when the rays of light reflected in the reflective unitare introduced into the image pick-up unit, whereby the images in therespective image pick-up directions which are obliquely above or belowthe horizontal plane are picked up by the image pick-up unit.

Preferably, the reflective unit is an isosceles triangular prism incross section with its vertical angle side directed to the forward orrearward side of the vehicle; and the left and right sides of the prismcorresponding to the isosceles of an isosceles triangle out of the threesides of the prism function as the two first reflective surfaces.

Preferably, the image pick-up unit includes an image pick-up elementwhose light receiving axis is so arranged as to be parallel to avertical plane which is parallel to the longitudinal direction, theimage pick-up element receiving rays of light reflected in thereflective unit, and an image forming lens disposed in optical paths ofthe respective rays of light between the image pick-up element and thereflective unit and is characterized in that the direction of the lightreceiving axis of the image pick-up element is rotated and adjustedwhile being held to be parallel to the vertical plane, whereby theincident axis is set to tilt vertically and obliquely with respect tothe horizontal plane.

Preferably, the image pick-up unit includes a reflective member suchthat the normal direction of its second reflective surface is soarranged as to be parallel to a vertical plane which is parallel to thelongitudinal direction; and rays of light reflected in a directionsubstantially parallel to the longitudinal direction are reflected froma second reflective surface in a direction substantially parallel to thevertical direction, an image pick-up element for receiving the rays oflight reflected in the reflective member, and an image forming lensdisposed in optical paths of the respective rays of light between theimage pick-up element and the reflective unit and is characterized inthat the direction of at least one of the normal of the reflectivesurface of the second reflective surface of the reflective member andthe light receiving axis of the image pick-up element is rotated andadjusted while being kept parallel to the vertical plane, whereby theincident optical axis is set to tilt vertically and obliquely withrespect to the horizontal plane.

According to the present invention, there is provided a method ofsetting the image pick-up directions of on-vehicle image pick-upapparatus comprising a reflective unit which is provided in the front orrear end portion of a vehicle and has two first reflective surfaces forreflecting rays of light incident from image pick-up directions on bothleft and right sides of the vehicle respectively in a directionsubstantially parallel to the longitudinal direction of the vehicle, andan image pick-up unit for picking up images in the respective imagepick-up directions by taking in the rays of light reflected in thereflective unit and is characterized in that the reflective surfaces ofthe reflective unit are disposed in parallel to the vertical directionof the vehicle; and the image pick-up optical axis of the image pick-upunit is set so that the incident optical axes of the rays of light maytilt vertically and obliquely with respect to a horizontal plane whenthe rays of light reflected in the reflective unit are introduced intothe image pick-up unit, whereby the image pick-up directions are set byadjusting the angle between the incident axis and the horizontal plane.

Moreover, according to the present invention, there is provided anon-vehicle apparatus for watching around a vehicle comprising an imagepick-up unit for picking up an image on at least one of the forward,left and right sides of a vehicle whereby to display the image thuspicked up on a display unit provided in the vehicle and to control themovement of the vehicle by processing the image and is characterized inthat the image pick-up unit is fitted to an opening grille formedoutside a vehicular radiator.

The on-vehicle apparatus for watching around a vehicle described mayinclude a cooling fan installed inside the opening grille and used forcooling the radiator.

Moreover according to the present invention, there is provided avehicular image pick-up apparatus for picking images around a vehicle byreceiving rays of external light passing through image pick-uptransmission windows disposed in a manner facing the outside of thevehicle, wherein a transparent hydrophilic film is formed on the outersurface of each of the image pick-up transmission windows.

Preferably, the hydrophilic film is a film having a contact angle of 20degrees or smaller with water and more specifically, a titaniumphoto-catalytic film is usable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view showing the construction of the principal part ofan on-vehicle image pick-up apparatus according to a first embodiment ofthe present invention.

FIG. 2 is a plan view of the construction of FIG. 1.

FIG. 3 is a diagram showing that rays of light from left and right imagepick-up directions are respectively reflected from the sides and of aprism in the construction of FIG. 1.

FIG. 4 is a diagram showing images displayed on a display unit, which ispicked up by the on-vehicle image pick-up apparatus of FIG. 1.

FIG. 5 is a side view showing the construction of the principal part ofan on-vehicle image pick-up apparatus as a variation of the on-vehicleimage pick-up apparatus of FIG. 1.

FIG. 6 is a plan view of the construction of FIG. 5.

FIG. 7 is an external perspective view showing an image pick-up unit,mounted in an automobile, of an on-vehicle apparatus for watching arounda vehicle according to a second embodiment of the invention.

FIG. 8 is a sectional view showing that the image pick-up unit, mountedin the automobile, of the on-vehicle apparatus for watching around avehicle according to the second embodiment of the invention.

FIG. 9 is a diagram showing the overall construction of the on-vehicleapparatus for watching around a vehicle according to the secondembodiment of the invention.

FIG. 10 is a diagram showing how images in the left and right visualfields are taken in by the image pick-up unit.

FIG. 11 is a block diagram showing an apparatus for watching around avehicle according to a third embodiment of the invention.

FIG. 12 is a schematic plan view of an image pick-up apparatus.

FIG. 13 is a diagram of an example of arranging a conventionalon-vehicle image pick-up apparatus in a vehicle.

FIG. 14 is a diagram of an example of arranging the conventionalon-vehicle image pick-up apparatus.

FIG. 15 is a block diagram showing the conventional apparatus.

FIG. 16 is a side view of the construction of the principal part of FIG.15.

FIG. 17 is a diagram showing the way of reflection of rays of light fromleft and right image pick-up direction on the sides of a prism in theconstruction of FIG. 15.

FIG. 18 is a diagram showing that the picked up images are displayed ona display unit.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The present invention will be described in detail with reference to theaccompanying drawings.

FIRST EMBODIMENT

FIG. 1 is a side view showing the construction of the principal part ofan on-vehicle image pick-up apparatus embodying the present invention;and FIG. 2, a plan view of the construction of FIG. 1. What makes anon-vehicle image pick-up apparatus 31 different from the on-vehicleimage pick-up apparatus 1 provided to the conventional apparatus forwatching around a vehicle shown in FIG. 15 is in respect of thearrangement of an image pick-up unit 15, wherein like referencecharacters are mutually given to corresponding parts and the descriptionthereof will be omitted. Like the conventional on-vehicle image pick-upapparatus 1, the on-vehicle image pick-up apparatus 31 according to thisembodiment of the invention is also provided in the front or rear endportion of a vehicle and together with a display unit 7 and the likeconstitutes an apparatus for watching around a vehicle.

In the on-vehicle image pick-up apparatus 31 according to thisembodiment of the invention, a prism 13 is disposed so that sides 13Land 13R of the prism are set parallel to the vertical direction of thevehicle as shown in FIGS. 1 and 2. The incident optical axes (i.e., theimage pick-up optical axis B of the image pick-up unit 15) of rays oflight 17L and 17R when the rays of light 17L and 17R reflected in theprism 13 are introduced into the image pick-up unit 15 are set tovertically tilt (upward in this case) at an angle Θ of inclination withrespect to a horizontal plane C, whereby images are picked up by theimage pick-up unit 15 in image pick-up directions 3L and 3R obliquelyupward or downward (obliquely upward in this case) with respect to thehorizontal plane C.

According to the first embodiment of the invention, the light receivingaxis of the image pick-up element 15 a of the image pick-up unit 15 isset parallel to a vertical plane in parallel to the direction of traveland vertically tilted with the respect to the horizontal plane.Correspondingly, the central axis of an image forming lens 15 b is alsoset coincident with the light receiving axis of the image pick-upelement 15 a.

Further, the direction of the light receiving axis of the image pick-upelement 15 a is rotated and adjusted while it is held parallel to thevertical plane, whereby the image pick-up optical axis B is set to tiltvertically (upward in this case) obliquely with respect to thehorizontal plane C.

Therefore, rays of light 17L′ and 17R′ on the incident optical axes outof the rays of light 17L and 17R reflected from the respective sides 13Land 13R of the prism 13 in the image pick-up directions 3L and 3R andincident on the image pick-up unit 15 are reflected at the reflectiveposition P of the sides 13L and 13R of the prism and incident on theimage pick-up unit 15 in such a state that they have been verticallytilted by an angle of Θ with respect to the horizontal plane C. In otherwords, the angle between the rays of light 17L′ and 17R′ before andafter being reflected at the reflective position P of the sides 13L and13R of the prism vertically comes up to 2Θ.

In the on-vehicle image pick-up apparatus 31, the images in therespective image pick-up directions 3L and 3R are consequently picked upwhile the image pick-up optical axis B defining the image pick-updirections 3L and 3R is set to tilt vertically (upward in this case)with respect to the horizontal plane C.

The image pick-up unit 15 may be held by a predetermined holder providedin the case 11 while the angle Θ of inclination of the image pick-upoptical axis B is set at a predetermined value. Otherwise, the imagepick-up unit 15 may be held in the case 11 by a holder with the functionof adjusting the angle for holding the image pick-up unit 15 rotatablyaround the axis along the left and right directions of the vehicle.

FIG. 4 shows an image picked up in case where the on-vehicle imagepick-up apparatus 31 according to the first embodiment of the inventioninstead of the image pick-up apparatus 1 in the conventional apparatusfor watching around a vehicle shown in FIG. 15. With the image pick-upapparatus 31 according to this embodiment of the invention, the takenimages of the bumper 9 are reduced as shown in FIG. 4 as the imagepick-up directions 3L and 3R have been set obliquely upward with respectto the horizontal plane. Consequently, the percentage of the images 21and 23 of the bumper 9 within the images taken is made lower.

As set forth above, according to the first embodiment of the invention,both the sides 13L and 13R of the prism as the reflective surfaces ofthe prism 13 are arranged so that they may be parallel to the verticaldirection and the image pick-up optical axis B of the image pick-up unit15 is set to tilt vertically (upward in this case) and obliquely withrespect to the horizontal plane C. As the images in the obliquely upwardor downward (upward in this case) image pick-up directions 3L and 3Rwith respect to the horizontal plane C are picked up by the imagepick-up unit 15, the image pick-up directions 3L and 3R can be setobliquely upward or downward (obliquely upward in this case) withrespect to the horizontal plane C depending on the conditions ofinstallation of the on-vehicle image pick-up apparatus 31 in the vehiclewithout tilting of upright images as objects to be picked up.

FIG. 5 is a side view of the construction of the principal part of anon-vehicle image pick-up apparatus 41 as a modified example of theon-vehicle image pick-up apparatus 31; and FIG. 6, a plan view of theconstruction of FIG. 5.

A reflective member 15 c is added to the image pick-up unit 15 in theon-vehicle image pick-up apparatus 41. The reflective member 15 c isarranged so that its normal direction of the reflective surface may beset parallel to the vertical plane of the direction of travel A. Therays of light 17L and 17R reflected by the prism 13 in substantiallyparallel to the direction of travel A are reflected by the reflectivesurface toward the downward side in the substantially verticaldirection. The light receiving axis of the image pick-up element 15 a isdirected upward in the substantially vertical direction and the rays oflight 17L and 17R reflected downward are received by the reflectivemember 15 c. Correspondingly, the image forming lens 15 b is disposed inorder that in the optical paths of the respective rays of light 17 a and17 b between the image pick-up element 15 a and the reflective member 15c, its central axis coincides with the light receiving axis of the imagepick-up element 15 a.

Further, the direction of at least one of the normal of the reflectivesurface of the reflective member 15 c and the light receiving axis ofthe image pick-up element 15 a is rotated and adjusted while being keptparallel to the vertical plane in parallel to the direction of travel A,whereby the image pick-up optical axis B of the image pick-up unit 15 isset to tilt vertically (upward in this case) and obliquely with respectto the horizontal plane C.

A preferred method of setting the image pick-up optical axis B includesa method of longitudinally rotating and adjusting the light receivingaxis of the image pick-up element 15 a in such a state that the normaldirection of the reflective surface of the reflective member 15 c is setobliquely forward and downward at an angle of 45° with respect to thehorizontal plane C; and a method of rotating and adjusting the normaldirection of the reflective member 15 c vertically in such a state thatthe light receiving axis of the image pick-up element 15 a is directedup the vehicle so as to make the light receiving axis cross thehorizontal plane C at right angles.

In this arrangement of the modified embodiment, the rays of light 17Land 17R in the image pick-up directions 3L and 3R are reflected twicefrom the sides 13L and 13R of the prism 13 and the reflective member 15c and then incident on the image pick-up element 15 a. Because anyinversion of the left and right images is not produced by thereflection, the advantage is that no image inversion process isnecessary in the processing portion 5.

SECOND EMBODIMENT

FIG. 7 an external perspective view of an automobile fitted with animage pick-up unit of an on-vehicle apparatus for watching around avehicle according to a second embodiment of the present invention; FIG.8, a sectional view of the image pick-up unit mounted in the automobile;and FIG. 9, a diagram showing the overall construction of the on-vehicleapparatus for watching around a vehicle.

As shown in FIGS. 7 to 9, the on-vehicle apparatus for watching around avehicle comprises an image pick-up unit 103 provided in such a manner asto be made inconspicuous by, for example, embedding it in the frontopening grille (radiator grille) 102 of a radiator 101 a in anautomobile 101 as an example of the vehicle, a display unit 104 such asan LCD (Liquid Crystal Display), CRT and the like provided in a positionwhere it is easily visible to a driver, that is, in an instrument panelinside the vehicle, and a signal processing portion 105 for convertingthe image single picked up by the image pick-up unit 103 to a displaysignal and supplying the display signal to the display unit 104. Thesignal processing portion 105 also processes the image to control themovement of the vehicle.

As shown in FIG. 9, the image pick-up unit 103 includes a rectangularcase body 110 extending along the longitudinal direction of theautomobile 101, a pair of lateral transmission windows 111 and 112 oftransparent glass fitted to the rectangular opening formed andpositioned on both the respective front side openings of the case body110, a CCD camera 113 as a single image pick-up portion disposed in thecase body 110, and a prism body 114 for guiding light onto the imagepick-up surface of the CCD camera 113 by reflecting the light introducedthrough the transmission windows 111 and 112.

At this time, light entering from the left transmission window 111 ispassed through one side 114 a of the prism body 114 and reflected fromthe other side 114 b thereof before being guided to the right half ofthe image pick-up surface of the CCD camera 113, whereas light enteringfrom the right transmission window 112 is passed through the other side114 b of the prism body 1144 and reflected form the one side 114 athereof before being guided to the left of the image pick-up surface ofthe CCD camera 113, so that both the left and right scenes in therespective left and right visual fields are simultaneously picked upthereby.

The image signal picked up by the CCD camera 113 is subjected to amirror image inversion process in the signal processing portion 105 andsupplied to the display unit 104. The right-hand side scene picked upthrough the right transmission window 112 is displayed in the right halfportion in the display portion 104 a of the display unit 104 as a rightimage, whereas the left-hand side scene picked up through the lefttransmission window 111 is displayed in the left half portion thereof asa left image.

As shown in FIG. 8, a cooling fan 116 for cooling the radiator 101 a isinstalled in the back portion of the radiator 101 a housed in the lowerfront end portion of the bonnet 115 of the automobile 101. An openinggrille 102 for taking in cooling air is fitted in the opening 118between the front end of the bonnet 115 and a bumper 117. The imagepick-up unit 103 excluding its front end portion where the transmissionwindows 111 and 112 are formed is housed in part of the opening grille102, for example, between adjoining fin portions 102 a and bonded to onefin portion 102 a by using a predetermined bonding means such asadhesive resin 119. In this case, the cooling fan 116 is automaticallyactuated when a prescribed temperature sensor (not shown) detects thatthe temperature of the radiator 101 a is rising. Therefore, sufficientcooling air is sucked by the operation of the cooling fan 116 in casewhere no satisfactory cooling effect is unavailable by natural airduring the travel of the automobile 101.

With the on-vehicle apparatus for watching around a vehicle that isarranged as described above, the left and right scenes in theintersection zone are simultaneously taken in through the respectivetransmission windows 111 and 112 of the image pick-up unit 103 providedin the opening grille 102 by causing only the front end portion of theautomobile 101 to enter the intersection zone at the intersection wherethe lateral visibility is poor as shown in FIG. 10. As the left andright scenes are simultaneously displayed on the display portion 104 ain the display unit 104 (FIG. 9) of the vehicle, the driver can checksafety on the left and right sides at the intersection at a time bylooking at the display portion 104 a, thus making it easy for the driverto confirm the safety.

Since the image pick-up unit 103 is arranged in the opening grille 102of the opening 118 for taking in cooling air in front of the radiator101 a of the automobile 101, the image pick-up unit 103 is cooled by thenatural air flowing into the opening grille 102 and the cooling airforced to be sucked into the opening grille 102 by the cooling fan 116in addition to the natural air during the travel of the automobile 101,whereby a cooling effect is satisfactorily secured in the image pick-upunit 103. The image pick-up unit 103 provided in the channel of thecooling air is also sufficiently cooled by forcing the cooling air to besucked into the opening grille 102 even during low-speed traveling oridling at the time of stopping, so that radiation of heat from the imagepick-up unit 103 can effectively be conducted.

Since the image pick-up unit 103, excluding its front end portion, isprovided so that it may be housed between the fin portions 102 a, theimage pick-up unit 103 never becomes conspicuous from the outside, thuspreventing the automotive design from being deteriorated.

Although it has been arranged that the suction type cooling fan 116 isemployed and placed on the rear side of the radiator 101 a according tothe second embodiment of the invention, any push-in type cooling fan 116may be employed and placed in front of the radiator 101 a. Even in thiscase, as the cooling fan 116 operates to suck cooling air for the imagepick-up unit 103 placed in front of the cooling fan 116, whereby theeffect of radiating heat from the image pick-up unit 103 is enhanced.

Although the description has been given of what is used to pick upimages on both sides around a vehicle as the image pick-up unit 103, itmay be the one used to pick up only an image in front of or one side ofa vehicle.

The image pick-up unit 103 has been provided in the opening grille 102in the front end portion of the automobile 101 according to the secondembodiment of the invention. In a vehicle model with an engine and aradiator which are mounted in the rear portion of the automobile 101,however, the image pick-up unit may be provided in the opening grillenear the radiator or engine in the rear portion of the automobile 101.Even in this case, it is preferable to install such an image pick-upunit in the rear (outside) of a cooling fan for sending or sucking airto or from the radiator or engine. Notwithstanding, the image pick-upunit 103 is used to pick up an image in the backward direction of avehicle or on both left and right sides of the rear periphery thereof.

THIRD EMBODIMENT

A third embodiment of the present invention will now be described.

First, a description will be given of the overall construction of anapparatus for watching around a vehicle to which a vehicular imagepick-up apparatus according to the third embodiment of the invention isapplied. As shown in FIG. 11, the apparatus for watching around avehicle is intended to display images obtained by picking up those onleft and right sides around a vehicle and equipped with an image pick-upapparatus 201 installed in the front bumper of an automobile as anexample of the vehicle, a display unit 210 formed with an LCD, CRT orthe like provided in a position where it is easily visible to a driveras in an instrument panel, and a control unit 211 for subjecting animage signal that is output from the image pick-up apparatus 201 to apredetermined process, supplying the processed image signal to thedisplay unit 210 and controlling the on and off states of the imagepick-up apparatus 201 and the display unit 210.

As shown in FIG. 12, the image pick-up apparatus 201 comprises a casebody 202, a camera unit 205 such as a CCD camera incorporating an imagepick-up element and a lens, and a substantially isosceles triangularpillar-like prism body 206 in cross section, the camera unit 205 and theprism body 206 being housed and disposed in the case body 202.

The case body 202 is a substantially rectangular parallelepiped in shapewhose long sides are extended in the longitudinal direction of theautomobile and whose first half portion 203 on both sides are tiltedforward from the center of the case body 202. Moreover, a substantiallysquare window opening 203 a is formed in the first half portion 203 onboth sides of the case body 202. An image pick-up transmission window204 formed of a transparent glass plate or the like is fitted into eachwindow opening 203 a, so that rays of light La and Lb from both therespective sides of the case body 202 can be passed through therespective image pick-up transmission windows 204 and introduced intothe case body 202.

The camera unit 205 is housed and disposed in the case body 202 with itsincident surface 205 a directed forward and simultaneously the prismbody 206 is also housed and disposed in the forepart of the case body202 and in front of the pick-up surface 205 a with its base sidedirected opposite to the pick-up surface 205 a.

The ray of light La passed through the right-hand image pick-uptransmission window 204 of FIG. 12 and introduced into the case body 202is reflected from the left side face 206 a of the prism body 206 andguided to the left half portion of the incident surface 205 a of thecamera unit 205, whereas the ray of light Lb passed through theleft-hand image pick-up transmission window 204 and introduced into thecase body 202 is reflected from the right side face 206 b of the prismbody 206 and guided to the right half portion of the incident surface205 a of the camera unit 205, whereby images of scenes on both left andright sides can simultaneously be picked up by the single camera unit205.

The control unit 211 controls the on and off states of the image pick-upapparatus 201 and the display unit 210 through a heretofore known methodaccording to a vehicle speed signal from a vehicle speed sensor (notshown), a signal indicating a brake operating condition, on and offsignals of any switch near the driver's seat (e.g., in case where it isdecided that an automobile is approaching an intersection, the displayunit 210 is caused to display images on both left and right sides of theautomobile by turning on the image pick-up apparatus 201 and the displayunit 210). Simultaneously, the image signal output from the imagepick-up apparatus 201 is subjected to a predetermined process so thatthe processed image signal can be applied to the display unit 210.

Further, the display unit 210 is adapted to display images on both leftand right sides of the automobile according to the image signal appliedfrom the control unit 211.

With the apparatus for watching around a vehicle thus arranged, atransparent hydrophilic film 208 is formed on the outer surface of eachimage pick-up transmission window 204 in the image pick-up apparatus 201in order to obtain less-distributed images from surroundings of thevehicle at the time of rain fall, vehicle body washing and the like. Thehydrophilic film 208 is a film having a contact angle of 20 degrees orsmaller, preferably 10 degrees or smaller with water, the film 208 beinga titanium photo-catalytic film provided with hydrophilic nature throughthe photo-catalytic action, for example. In case where rain drops,washing water drops and like stick to the outer surface of such atransmission window because of rain fall, vehicle body washing and like,the water drops uniformly spread on the surface of the hydrophilic film208 to form a thin water film.

With the image pick-up apparatus 201 thus arranged, as water dropssticking to the outer surfaces of the image pick-up transmission windows204 make thin water films uniformly spreading on the surfaces of therespective transparent hydrophilic films 208, the refraction andscattering of the rays of light La and Lb hardly occur when the rays oflight La and Lb pass through the respective image pick-up transmissionwindows 204 and enter the case body 202. Therefore, it is possible toobtain less-disturbed images around the vehicle after rain fall, vehiclebody washing and the like.

Since water drops sticking to the outer surface of each image pick-uptransmission window 204 form a thin water film uniformly spread on thesurface, the water drops falling onto the image pick-up transmissionwindow 204 are caused to go down along the water film and allowed toeasily flow downward by vertically providing the facial direction of theimage pick-up transmission window 204. Thus, a relatively thin waterfilm is maintained, whereby less-stained pick-up images are obtainable.

Moreover, the thin water film thus formed is dried quicker and becomesextinct as compared with the case where water drops are sticking on theimage pick-up transmission window 204 without the hydrophilic film 208.Hence, the water drops formed on the outer surface of the image pick-uptransmission window 204 becomes extinct in a relatively short time evenafter rain fall and vehicle body washing. Good original images are thusobtainable.

Although the description has been given of the example applied to theapparatus for watching around a vehicle wherein the image pick-upapparatus 201 is designed to pick up images on both left and right sidesof the surroundings of a vehicle and to display the images on thedisplay unit 210 within the vehicle according to the third embodiment ofthe invention, the invention is not limited to such an embodiment. Forexample, the images obtained from the image pick-up apparatus 201 aresubjected to a predetermined imaging process to detect any automobile orthe like approaching an intersection from the left or right side wherebyto warn the driver in the other vehicle using a buzzer or a voice, or towarn, with warning unit 212, the other approaching vehicle using a radiowave, light, an ultrasonic wave or the like. Otherwise, a radio wave,light, an ultrasonic wave may be used to give notice to a predetermineddisplay unit installed on the road side using an ultrasonic wave or thelike.

Although it has been arranged that the rays of light La and Lb from bothsides are incident on the incident surface 205 a of the camera unit 205via the prism 206, rays of light in front of the image pick-up surface205 a may be so arranged that they are directly incident on the pick-upsurface 205 a by disposing the pick-up surface 205 a in front of theimage pick-up transmission windows 204 having the hydrophilic films 208.

According to the invention, the first reflective surfaces of thereflective unit are disposed in parallel to the vertical direction ofthe vehicle, and the image pick-up optical axis of the image pick-upunit is set so that the incident optical axes of the rays of light maytilt vertically and obliquely with respect to a horizontal plane whenthe rays of light reflected in the reflective unit are introduced intothe image pick-up unit, whereby the images in the respective imagepick-up directions which are obliquely above or below the horizontalplane are picked up by the image pick-up unit. Therefore, the imagepick-up directions can be set obliquely upward or downward with respectto the horizontal plane depending on the conditions of installation ofthe on-vehicle image pick-up apparatus in the vehicle without tilting ofupright images as objects to be picked up.

According to the invention, as the image pick-up unit for picking up animage on at least one of the forward, left and right sides of a vehicleis fitted to the opening grille for sending air to the radiator, ahigh-level effect of radiating heat from the image pick-up unit can besecured. Moreover, the provision of the image pick-up unit in theopening grille will never deteriorate automotive design.

According to the invention, the effect of radiating heat from not onlythe radiator but also the image pick-up unit is ensured only byactuating the cooling fan.

According to the invention, the vehicular image pick-up apparatus forpicking images around a vehicle by receiving rays of external lightpassing through the image pick-up transmission windows disposed in amanner facing the outside of the vehicle such that the transparenthydrophilic film is formed on the outer surface of each of the imagepick-up transmission windows. Therefore, even though rain drops and bodywashing water drops and the like stick to the outer surfaces of therespective image pick-up transmission windows, the refraction andscattering of the rays of light hardly occur when the rays of light passthrough the respective image pick-up transmission windows as the waterdrops form a thin water film uniformly spread on each hydrophilic filmsurface. Less-disturbed images around a vehicle are thus obtainable evenafter rain fall and vehicle body washing.

1. An apparatus for watching around a vehicle, the apparatus mountedthereon, the apparatus comprising: an image pick-up unit, having areflective portion and an imaging portion, for picking up an image to aleft side and a right side at the front of the vehicle, the imagepick-up unit fitted to an opening of a grille formed outside a vehicularradiator with respect to a vehicle operator, only the reflective portionof the image pick-up unit extending beyond the grille, reflectivesurfaces of the reflective portion disposed in parallel to a verticaldirection of the vehicle and the imaging portion taking in the imagereflected by the reflective portion; a display unit for displaying theimage, the display unit provided in the vehicle; a control unit forprocessing the image to enable the vehicle operator to control themovement of the vehicle based on the displayed image; and a warning unitcoupled to the control unit and transmitting a warning signal to a userof another vehicle, wherein an image optical axis of the imaging portionis set so that incident optical axes of the image tilt vertically andobliquely with respect to a horizontal plane when the image reflected inthe reflective portion are introduced into the imaging portion and theimaging portion picks up the image in respective image pick-updirections which are obliquely above or below the horizontal plane. 2.The apparatus as claimed in claim 1, wherein a cooling fan for coolingthe radiator is provided inside the opening grille and between the imagepick-up unit and the vehicle operator.
 3. The apparatus as claimed inclaim 1, the warning unit comprises at least one of a buzzer, a voicegenerating unit, light generating unit, and radio wave generating unit.